A dewandre



Aug. 30; 1927.

A. DEWANDRE POWER BRAKE INVENTOR d fl-n a/rae BY Original Filed March 13. 1924 A TTORNEY.

Reissued Au g 30,1927.-

UNITED STATES This invention relates to power brakes, in which the braking force is produced by the action of the partial vacuum created by the suction of the engine and-transmitted to a cylinder, I

to the brakes. The control of these known brakes is eflected by means of a distributor, which places the brake cylinder n communication alternately with the engine suction and the atmosphere; the action of the .d1s-' tributor being governed by a control lever which may be either the brake pedalor a hand lever, but which, when many position, may be. further braking action. r My invention has for its olnect the provision of means such that the efiort for actuating the distributor increases with'the braking thereby being enabled to obtain an exact 1ndication of the braking action.

According to the invention, the piston of the motor brake is connected to the brakes by suitable members 'which are also connected to the control lever, so that when the brakes are in action, these .members exert tion of the pressure of the brakes and which is transmitted to the operator.

In the accompanying draw ng: Figure 1 is a perspective view of one embodiment of the invention; and I Figure 2 is an enlarged detail view of a lost-motion device-comprised in the connection between the control lever and the brake rodding, and the distributor w th wh ch such device is operatively associated, the parts being in the positions occupied when the brake action is being held.

Figures 3, 4, and 5, are diagrammatlc views illustrating the various positions of the lost-motion device and the distributor valves. f 5 Referring more particularly to the drawing, 3 indicates the cylinder of the brake motor, 4 the piston operatively disposed therein, and 1 3 the control lever (here shown as the brake pedal). The displacement of piston 4 is obtained by the partial vacuum created by the suction of the engine, in a out No. 1,539,166 granted May 26, 1925; such vacuum being transmitted to said cylin which works a piston connected moved by an efiort inde-- pendent of and not counteracted by the effort on the wheels, the operator on the said lever a reaction which is a frac,-

' manner similar .to that disclosed in my Pat I R 16,724 PATENT OFFICE.

Ali BERT DEWANDBE, OF LIEGE, BELGIUM, ASSIGNOB TO SOCIETE ANONYHE SERVO- FBEIN' DEWANDBE, OF LIEGE, IBELGIUK.

BRAKE.

Original 110. 1,603,750, elated October 19, 1926, Serial No. 699,022,411ed Batch 13, 1924, and in Belgium February 12,1924. Application for reissue filed May 17, 1927. Serial No. 192,126.

inder by the distributor, as hereafter e1;- plained.

Referring to Figure 2, which shows the distributor in detail, it will be observed that this device comprises two valves 8 and 9, which respectively control communication of the brake cylinder?) with the engine suction, through duct 2, and-with the atmosphere through opening 7 both valves being normally pressed toward-their seats b an interposed spring 11. The suction val ve 8 controls suction communication with the cylinder 3 through an openin 8 and conduit 8", indicated in dotted 'nes in Figures l and 2, the air valve 9 controlling atmospheric admission-to the cylinder through- "an opening 9' and a conduit 9" in open communication with the conduit 8", as indicated in dotted'lines in the figures referred to. The air valve 9 is mounted to slide on the stern-of the suction valve 8, and 1S opened by being pushed to the left by'a lever 10; while the suction-valveS is opened" '1 by being pulled to the right by said lever 10 engaging an abutment 44, on the stem of the valve. The operation of this lever 10 is effected in onedirection by -a Bowden shaft which acts in the same way as the shaft in the patented construction, the forward end of the wire 12 being fastened to said lever at one end, while the forward end of the sheath 12' of the shaft is'secured in a fixed sleeve 12 or other stationary part.

The piston 4 is connected to one end of a. lever 29. Adjacent the other. end 32, of lever 29, are pivotally connected the inner ends site directions, and are themselves connected respectively, to the brake rodding 6 and through a lost motion connection to a rod 33 actuateditby and pivoted to the control lever of'pedal 13. The end 32 of the lever 29 is pivotally connected by a link with a balancing lever 34, which is pivoted at one end to a fixed point on the frame, and pivoted at its other end to one end of a rod 35, whose opposite end is rigidly joined to of two rods 30 and 31. that extendin opporod'33. The outer end of the rod 31 is provided with a fork 36 (see Figures 2), the two arms of which are formed with elongated slots 37, in which may slide the ends of a cross-pin 38, secured at the junction of the rods 33 and 35. The rear end of the sheath 12 of the Bowden shaft is attached to the head 38" of pin '38, and the rear end of the wire 12 thereof is fastened to a lug or bracket 36' on fork 36.

Due to the above-described arrangement, assuming theparts are at rest, as shown in Figure 3, it Wlll. be apparent that depression rods 31 and 33 thus forming the two movably-related parts of a. lost-motion connection. Now the pin 38 has attached to it one end of the sheath 12 of the Bowden shaft, the other end of which is secured to the fixed point 12 on thedistributor, so that as a result of the increased distance between thexp'in-carried end of the sheath and the adjacent end of the wire 12 a force is exerted upon the wire which causes it tomove lever 10 counter-clockwise in the direction of arrow X (Figure 2), whereby said lever is rocked on its ivot which permits spring 11 to first close t e valve 9, as shown in Figure 4, and then lever 10 engages the abutment 44 on the stem of the'suction valve 8, and opens that valve, as shown in Figure 5. This connects the brake cylinder 3 with the engine suction, with the result that piston 4 is drawn forward and pulls lever 29 in the same direction; said lever rocking about ,its end 32 as a fulcrum, and moving with it the rod 30, which exerts a bra king effort on the rodding 6. Rod 31 is also. moved in the same direction as rod 30 and, hence, decreases the distance between the fork-carried end of the wire 12 and the pin-carried end of the sheath 12 of the Bowden shaft, so that the wire then slacks and the spring 21, connected to the distributor lever 10, moves back the latter to a neutral position, and spring 11 then acts to close the suction valve, and at the same time still hold the air valve 9 closed, as'shown in Figure 4. Further depression of the pedal will have the effect of again increasing the distance between the aforesaid ends of the twoparts of the Bowden shaft, so that lever 10 will open the suction valve, and a fresh braking efiort will be applied to the brakes.

In the initial operative movement of the pedal 13, the rod 33, rod 35, lever 34, and end 32 of lever 29 are moved in the same direction, that is, toward the left in Figure 1. In this movement, lever 29 swings on connection with'rod 30 as a center, the piston 4 moving slightly.

vThe operative swinging or pivotal movement of lever 29 produced consequent upon the introduction of the partial vacuum into' cylinder3, takes place about its end 32 as a support, such movement being transmitted through rod 30 to the brake rodding 6 to appl the brakes. On the continued for- .war movement of the piston, however, the

lever 29 would tend to rock about its point of connection with the rods 30 and 31 as a fulcrum or pivot, because said lever 29 is rocking on its end 32 as a su ort, and such end 32 is'substantially fixe by the pedal. That being so, the attempted clockwise rock ing movement of lever 29, about its new ful-. crum point, reacts against lever 34 exerting a pull-thereon to the'right in the direction of the arrow in Fi re 1, and, consequently, the rod 35 and ro 33 exert on the pedal 13 an efli'o'rt which increases in direct proportion with the efiort exerted on the brakes and which is directed in the opposite direction to that exerted thereon by the operator. But that effort is only a fraction of the effort exerted on the brakes, so that the operator is thus enabled to obtain an accurate indication of the extent or degree of the braking action. The value of the braking action is dependent not on the position of the brake lever or pedal, but on the pressure exerted by the foot of the operator on said pedal.

When the pressure on the pedal is relieved,

the pedal comes back carried by rods 33 and 35 on account of the reaction effect, said rods 33 and 35 carrying pin 38 with it to. the right. This movement of said rod decreases the distance between the end of the wire 12 carried by fork 36 and the end of sheath 12' carried by pin 38; and as a result of such decrease, the distributor. lever 10 under the action of spring 21 is swung to the left or clockwise (Figure 2) so as to open the air valve '9. The. cylinder 3 is thereby connected with atmosphere, and piston 4 is forced vto the right by the usual return spring (not shown).

Of course, it is apparentthat atmospheric valve 9 is held in normal pull of spring 21, and that in this position valve 8 is closed.

What I claim is:

1.', In a brake system for motor vehicles, the combination, with rodding forthe brakes, of a brake cylinder; a piston in said cylinder subjected to pressure differences; a brake lever; and a connection between the piston and the brake rodding for transmitting the movement of the former to the latter, said connecticn being 'operatively reposition by the lated to said lever so as to exert thereon a reaction which is a fraction of the pressure of the brakes,

2. In a brake system for motor vehicles, the combination, with rodding for the brakes, of a brake cylinder; :1 piston in said cylinder subjected to pressure differences; a brake lever having a lost-motion connection with the rodding; and a mechanical connection between the piston and the brake rodding for transmitting the movement of the former to the latter, said connection being operatively related to lever so as to exwhereby the'bra-king efiort of the po'wer-actuated element is divided in a definite ro-.-

- portion between the brake-applying me ium ert thereon a reaction which is, a fraction, of

the pressure of the brakes.

3. In a brake system for motor vehicles,

the combination, with rodding. for the brakes, of a brake cylinder; a piston in said cylinder-subjected to pressure differences; a

control lever havin a: positive connection with the brake rod ing; a lever connected to the first lever and a mechanical connection between the piston, the rodding and the second-named lever to transmit the movement of thepiston to the rodding and to exert simultaneously on the first lever,

'throu h the intermediary of the secondname lever, a reaction which is a fraction.

of the pressure of the brakes.

4. In a brake system .for motor vehicles,- the combination, with rodding for the brakes, of a brake cylinder; :1 piston in said cylinder subjected to pressure differences; a brake lever; anda lever system connecting the piston and the brake 'roddin'g for transmitting the movement of the former to the latter, said lever 's stem being opera, tivel related to the bra 'e lever so as to exert t ereon a reaction which is a fraction of the pressure of the brakes.

5. A brake system, according to claim in which the lever system embodies a lever which is connected at one end to the piston and at two other points to the brake rodding and brake lever, respectively.

6.1K brake system, according to claim 4 -in which the lever system "embodies a lever which is connected at one end to'the piston, and an intermediate lever which is attached to the brake lever the first-named lever be ing additionally connected at one point to the intermediate lever and at a second point to the brake rodding.

7. In a power brake system for 'automo-- biles, a manual control element, a power utua-ted element, a. mechanical connection be'-;

tween said two elements, and a brake-applying medium attached to said connection at point intermediate said two elements,

.and the manual control element.

.8. Ina power brake system for automobiles, a manual control element, a poweractuated element, a floating lever connected to both of said elements, and a brake-apply ing medium connected to said lever at a point intermediate its connection with said elements, whereby the braking effort of the power-actuated element is divided in a definite proportion between the brake-applying medium and the manual cont-r01 element.

' 9. In a power operated brake system for automobiles, a power means subjected to pressure differences, a brake applying mechanism operated by the power means, a manually-operated element, a valve mechanism operated by said element for controlling said pressure difierences, and means independent of said valve mechanism whereby a constant proportion of such ressure difi'erences is transmitted to sai erated element in opposition .0 manual influence, wherebyany resultant effect of such pressure dlfierences has a fractional reaction against such manual influence to thereby indicate the effective pressure diflerences otthe power means.

10. Ina braking mechanism for automobiles, a poweractuator responsive to the suction of the engine for brake application, a manually-operable element for controlling such power actuator, braking means respon sive to .the power actuator for applying and releasing the brakes, and means responsive to the full movement of the power actuator when operatin under engine suction to exmanually-opert a fractiona part of suchpower on the manually-operated element in opposition to the manual influence thereon.

11. In a brake mechanism for automobiles,

a cylinder, a piston within the "cylinder,

,means' whereby the piston maybe subjected to pressure differences, a manually-operable element-for controlling said means and thereby. such pressure difi'erences, connections'leading to the bra-ke's 'and operated b the movement of such piston, and indepem ent means whereby the pressure differences on the iston are at all times proportionally. directed to create a reaction on said manually-operable element'against the manual in- 'fluence;

1 12; In a brake system for motor vehicles,

the combination of power means subjected to ressure ditl'erences,brake-app ying mechamsm operated by the power means, a brake lever for controlling said pressure difierences, and a connection operatively related to. Said brake-applying mechanism and to said lever so as to exert on said lever a reaction which is a fraction .of the pressure of, the brakes.

13. In a brake system for motor vehicles, the combination of power means subjected to pressure differences, brake-applying mechanism operated by the power means, a brake lever for controlling said pressure difierences, and an element directly and proportionally operated by the power means, said 1 element acting to exert on the brakelever a reactive force commensurate with its operatlouby the power means.

14. In :1 brake system for motor vehicles,

the conibination, with rodding for the brakes, of a brake cylinder; :1 piston in said cylinder sulnected to pressure differences; a brake lever; and means between the piston and the brake rodding for transmitting the movement of the former to the latter, said means being operatively related to the brake lever so as to exert thereon a reaction which nism, a valve for controlling communication ofthe cylinder with the suction of the engine,'a valve for controlling communication of the cylinder with the atmosphere, a manually operable element, and means arranged between the manually operable element and the valve and including parts arranged for a limited free relative movement to permit the operation of the element to first close the valve controlling atmospheric admission to the cylinder and thereafter open the valve controlling suction admission to the cylinder, said means being capable of a position in whichboth valves are closed and incapable of a position in which both valves are simultaneously opened, and means whereby the power incident to the suction admission to the cylinder may be proportionally directed to the manually-operable element in opposition to the manual influence thereon to constitute a reaction influence on the foot of the operator proportioned relative to the braking power.

16. A brake system for motors, including braking mechanism, a brake cylinder having a piston connected with the braking mechanism, a valve for controlling communication of the cylinder with the suction of the engine, a valve for controlling communication of the cylinder with the atmosphere, it manually operable element, and a connect-iondntermediate the manually operable element and the valves and including .a lost motion part influenced by the manually operable element and by the braking mechanism, said connection, when operated by the manually operable element through ,the lost motion part, serving to close the valve establishing communication between the atmosphere and cylinder and thereafter open the valve estabhshing communication between the suction of the engine and the cylinder to move the piston to operate the braking mechanism,

the operative movement of the braking mechanism serving through the lost motion part'of said connection to permit closing of the valve vfor controlling t e suction of the engine to the cylinder without afiecting the previously closed valve. for controlling atmospheric admission to the cylinder, thereverse movement of said manually operable in opposition to the manual influence thereon to constitute a reaction influence on the foot of theoperator proportioned relative to the brakin power.

17. In a rake system for motor vehicles, I i

the combination with rodding for the ,brakes, of a brake cylinder, a piston in said cylinder subjected to ressure differences, a manually-operable-bra e lever, valve mechanism'operated by said lever for controlling said pressure difierences and means independent of said valve mechanism whereby the power incident to the pressure'difierences or on the piston may be proportionall directed to the brake lever in opposition to t e manual influence thereon, to constitute a reaction influence on. the foot' of the operator proportioned relative to the braking power.

In testimony whereof I aifix my signature.

ALBERT DEWANDRE. 

